patch 8.1.0048: vim_str2nr() does not handle numbers close to the maximum

Problem:    vim_str2nr() does not handle numbers close to the maximum.
Solution:   Check for overflow more precisely. (Ken Takata, closes #2746)
diff --git a/src/version.c b/src/version.c
index d290fda..fc68f8e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    48,
+/**/
     47,
 /**/
     46,